Keyway cylinder removal tools or “lock pullers” of various types are known in the art. Typically, lock pullers permit the pulling of the “plug” from cylinder locks for replacement purposes. One type of destructive entry tool used by locksmiths that can extract either the entire cylinder or the plug alone from a safe deposit box and thereby provide access to the locking mechanism is the so-called “Bell” cylinder puller. In order to use the Bell device, a threaded fastener; typically a wood screw, is screwed into a keyway of a plug where it is held fast. The head of the fastener is temporarily retained by a portion of the tool that is coupled to one end of a lead screw positioned longitudinally within a cylindrical housing. At the end of the lead screw opposite the screw retaining portion is a hex nut. When the hex nut is turned, e.g., by a wrench, the retainer moves in an opposite direction to the housing which is braced against the mounting face of the lock, thereby drawing out the cylinder plug. The majority of destructive entry tools currently employed for removal of cylinder locks for replacement purposes are variants of the Bell device.
Other types of plug extractors have been described in the past. U.S. Pat. No. 4,707,903 to McCartney describes a nose plug puller for rekeying a Mosler type safe deposit box lock which includes a pull shaft that is partially threaded, a support, a nut and a cam key. Although the McCartney device teaches these as separate elements, when assembled, the device operates similarly to the Bell device whereby a cylinder plug is pulled by turning a lead screw. The plug is pulled by using the lock mounting surface to push against.
U.S. Pat. No. 6,725,697 to Leadon describes a keyway cylinder plug removal tool for a safe deposit box that uses a hole saw to cut through the retaining lip portion of a nose surround to free the plug.
While working well for their intended use, the foregoing devices are time consuming due to the number of turns required of the lead screw in order to draw out the cylinder plug; a distinct disadvantage in cases where multiple locks must be replaced en masse.
It would be desirable to provide a lock puller that extracts plugs much more rapidly than previous devices.
It would be desirable to provide a lock puller that performs the forgoing extraction without damage to either the face plate or plug surround.
It would be further desirable if such a lock puller were easy to use, requiring little practice in order to gain proficiency.
It would be especially desirable if the lock puller were readily adaptable to the majority of safe deposit box locks in use.